1. Technical Field
The present invention relates to the technical field of, for example, a capacitor element, a method for manufacturing the same, and an electro-optic device such as a liquid crystal device, which includes the capacitor element as a holding capacitor.
2. Related Art
In a liquid crystal device which is an example of this sort of electro-optic device, a holding capacitor is provided corresponding to each pixel portion so that an image signal supplied to a pixel electrode is temporarily held. Such a holding capacitor includes a pair of capacitor electrodes and a dielectric film formed between the capacitor electrodes. The pair of capacitor electrodes is electrically connected to wiring provided in a layer different from a layer in which the holding capacitors are formed on a substrate, and constitutes a portion of a circuit portion on the substrate. Japanese Unexamined Patent Application Publication No. 2008-058578 discloses a technique in which for enhancing the efficiency of a process for manufacturing a liquid crystal device, a step of forming contact holes for electrically connecting different layers on a substrate is omitted.
When among the pair of capacitor electrodes, an upper electrode formed above a lower electrode is electrically connected to wiring formed below the holding capacitor, a dielectric film interposed between a pair of electrodes is patterned to a predetermined shape using, for example, an acid etching solution or the like.
However, when a dielectric film is etched with an acid etching solution, the dielectric film is easily etched, and thus it is difficult to pattern the dielectric film into a predetermined shape. For example, when a dielectric film of alumina or the like is formed for increasing the capacitance value of a holding capacitor, the dielectric film of alumina may be formed at a low temperature, and the dielectric film of good quality, which has low leakage current, is formed. However, the dielectric film is easily etched with an acid etching solution. Therefore, even when the dielectric film is formed using a dielectric material which can improve electric characteristics of the dielectric film, there occurs the problem that patterning is difficult by a process for forming holding capacitors.
Such a problem may occur in not only a holding capacitor provided for each pixel portion of a liquid crystal device and a capacitor element in which an upper electrode, which is one of a pair of capacitor electrodes, is electrically connected to a conductive portion provided below the capacitor element.